A magnetotelluric investigation of the San Andreas Fault at Carrizo Plain, California

High quality, wide‐band magnetotelluric data were collected along two profiles crossing the San Andreas fault at Carrizo Plain, California for crustal imaging as part of the San Andreas Deep Drilling Project. Two‐dimensional inversions of the data indicate that the upper crustal part of the San Andreas fault does not appear here as an anomalously conductive zone. Additionally, a broad resistive zone under the Temblor Mountains (east of the fault) suggests resistive crystalline or metamorphic rocks may be present here as opposed to the more conducting Franciscan assemblage, contradicting the generally‐accepted geologic model.